As dozens of burned children poured into a Syrian hospital, crying out in agony, their injuries were so terrible that a British doctor struggled to find enough undamaged skin to insert a drip.

"Some of them were so badly burned you couldn't even find a patch of skin to put an intravenous line through," said Dr Saleyha Ahsan. "They were schoolkids. They had all been together in their school."

Dr Ahsan, a volunteer in a Syrian hospital, treated children who were caught in a ball of flame when a jet fighter dropped an incendiary bomb outside their school last Tuesday. This overwhelmed facility in a rebel-held area of northern Syria helped 25 victims, of whom eight died.

Dr Ahsan, who normally works in Accident and Emergency at Queen's Hospital in Romford, Essex, personally treated 10 casualties. Yesterday, she gave The Daily Telegraph a detailed account of this incident, which ranks among the most disturbing of Syria's civil war.

Footage of the aftermath of the incendiary attack, shown by the BBC, has led some MPs who opposed British military action against Syria's regime to reconsider their stance.

"All of the ones I treated were teenagers aged 14 to 18, apart from one who was a girl of eight," said Dr Ahsan.

The first that she knew of the incident was when casualties began pouring into the hospital, covered in the white residue of an incendiary device. Strips of incinerated skin hung from their bodies.

"Suddenly ambulances arrived at the door with lots of screaming," she remembered. "I turned around to see people walking in covered in what seemed like white powder. In a matter of minutes, it became a mass casualty incident."

Dr Ahsan and the rest of the staff tried to salve the searing burns by dousing their patients with cold water. Whatever remained of the children's clothes was torn away, allowing them to be covered in cool liquid. But water therapy provides only minimal and temporary relief.

The next stage was to cover the casualties in burn relief cream and insert intravenous drips. "At one point, it was hard to see if it was their clothes hanging off them, or their skin. It was all mixed together," said Dr Ahsan. "It was the worst incident that I've ever seen in terms of burns."

Many patients also required oxygen, but the small hospital possessed only two canisters. Dr Ahsan found herself struggling to help one of the youngest victims: an eight-year-old girl. "She had severe facial burns and her face was covered in cream. I didn't realise she was so young."

According to the patients, the jet's deadly payload had exploded outside their classroom in the middle of a maths lesson. The surviving children have been transferred to hospitals in Turkey, but Dr Ahsan said that even with the best care, their lives were in the balance. "With burns, the bigger the area affected," she said, "and the younger the patient - the worse the likely outcome."